Motor controlled valve for continuously feeding viscous liquids

ABSTRACT

Disclosed herein is a motor driven needle valve, with a manual override arrangement, for controllably feeding a stream of massecuite into a continuous centrifugal separator.

United States Patent 1191 Laven Nov. 5, 1974 l l MOTOR CONTROLLED VALVEFOR CONTINUOUSLY FEEDING VISCOUS [56] References Cited LlQUlDS UNITEDSTATES PATENTS Inventor: Thomas Laven, Hamilton, OhiQ 1,966,209 7/1934Miller 251/130 [73] Assignee: The Western States Machine CompanyHamilton Primary Examiner-Robert NIISOI] Attorney, Agent, or Firm AlbertC. Johnston [22] Filed: Oct. 3, 1973 pp 403,071 57 ABSTRACT Disclosedherein is a motor driven needle valve, with a [52] US. Cl 137/604,251/122, 251/130, manual override arrangement, for controllably feeding251/134 a stream of massecuite into a continuous centrifugal [51] lnt.Cl. Fl6k 19/00 separator.

5 8] Field of Search 137/604, 605, 25 Mia/112326 8 Claims, 3 DrawingFigures MQTOR CONTROLLED VALVE FOR CONTINUOUSLY FEEDING VISCOUS LIQUIDSIn general, the present invention is directed broadly to continuouscentrifuges of the type commonly employed for separating liquid andsolid components of a viscous mixture such as massecuite. Moreparticularly, the present invention relates to a new and improved needlevalve apparatus for directing a stream of viscous liquid material intothe basket of a continuously rotating centrifugal machine such as is incommon use by the sugar refining industry for the separation of motherliquor and wash liquid from sugar crystals. Representative systems andapparatus for controllably and continuously delivering massecuite tocentrifugal separators are shown and described in US. Pat. Nos.3,223,283 and 3,393,805.

As discussed at length in the aforementioned patents, it is highlyimportant to the efficiency of the separating operation that themassecuite be delivered into the rotating basket of the centrifuge at asubstantially constant rate and in a uniform freely pouring stream. Inother words, the pouring massecuite stream must be maintained as freefrom variation as possible. Accordingly, in these and other earlierfeeding systems for controlling the flow of massecuite, efforts havebeen made to improve the control of and the characteristics of themassecuite stream which is delivered into the continuously rotatingcentrifugal basket. It is to such improvements that the presentinvention is specifically directed.

More particularly, in accordance with the present invention, a new andimproved motor driven control valve having a manual override controlelement is provided, whereby the size of the valve opening formed at acircular outlet orifice and thus the size or flow rate of a stream ofmassecuite or like material pouring by gravity from the orifice isprecisely determined by the positioning of a conical surface of agenerally teardrop shaped needle that is movable axially relative to theorifice. The needle is supported on a stem which is displaceable axiallyby the rotation of a lead screw through a suitable drive transmission,such as a worm gear unit, driven by electric, pneumatic or hydraulicmotor means in response to an appropriate control signal, for example,by a signal automatically generated by a servo control of known natureassociated with the power supply circuit of the basket drive motor, andthe valve stem is also displaceable axially relative to the lead screwby the manual operation of a handwheel associated therewith, so that thevalve orifice can be closed or opened, or the size of the openingvaried, independently of the motor.

The new valve may be mounted with its outlet orifice located at or evenbelow the plane of the top rim of the continuously rotated centrifugalbasket. Thus, the stream of massecuite falls only a short distance andis subjected to but minimal extraneous influences as it flows from thevalve orifice to the desired point of delivery in the basket.

Further in accordance with the invention, the supporting means for thevalve stem includes provisions for the introduction of a fluid treatmentmedium, such as water, steam or syrup, into the center of the massecuitestream flowing toward and from the outlet orifice of the valve. Thetreatment fluid enters the valve through a radial port communicating viaa manifold with axially disposed conduits which deliver the fluid aboutthe needle stem upstream of the orifice. As will be understood, thetreatment fluid will be mixed with the viscous massecuite passingthrough the valve structure and into the centrifugal basket.

The new valve provides simple, efficient, and reliable control for thefeeding of a free flowing massecuite stream. The foregoing and otherfeatures and advantages of the present invention will become apparentfrom the following detailed description of a preferred embodimentthereof taken in conjunction with the accompanying illustrativedrawings, in which:

FIG. 1 is a front elevational view of a valve embodying the principlesof the present invention, which valve is mounted immediately above thecentrifugal basket of a centrifugal extractor (shown in cross section);

FIG. 2 is a vertical, cross-sectional view of the new valve of thepresent invention taken along line 2-2 of FIG. 1, and

FIG. 3 is an enlarged horizontal, cross-sectional view of the new valvetaken through line 33 of FIG. 2.

Referring now to FIG. 1, a new and improved motor driven variable feedvalve 10 with a discharge orifice 20 is mounted in the plane of theupper rim of a perforated conical basket 11, which is mounted on shaft12 for rotation about a vertical axis. The shaft 12 is driven by belts13 in known fashion to rotate the basket 11 at high speed for thecentrifugal separation of the components of the charge material,typically sugar massecuite, fed therein through the valve 10.

In accordance with the invention, the discharge outlet 20 of the new andimproved valve structure 10 is selectively controllable between a fullyopen position and a closed position. In the fully open position, aconical needle 31, mounted on a longitudinal stem 35, is substantiallyfully retracted within the valve body to define an annular gap betweenthe conical surface of the needle 31 and the circular opening 32 of anorifice plate 33 mounted at the lower end of the valve body 34. In theclosed position shown in FIG. 2, the needle 31 is seated in contact withthe circular opening 32, eliminating any annular gap therebetween, andthereby completely closing the discharge outlet 20 to stop flowtherethrough.

As an important aspect of the invention, controlled selectivedisplacement of the needle 31 with respect to the opening 32 in theorifice plate 33 is effected by the translation of the stem 35 by amotor driven lead screw 36 threadingly engaged with the internal thread23 of a drive nut 37 carried by a manually operable control element inthe form of a handwheel 38. The nut 37 is fastened to the hub 39 of thehandwheel by exterior thread 22. As shown in FIG. 2, the handwheel 38 isfixedly attached through the hub 39 and set screw 40 to the upper end ofthe needle stem 35, and may be used to position the valve stem 35, withrespect to the orifice, independently of the operation of the motordrive for the lead screw 36.

As a further aspect of the invention, the upper portions of the needlestem 35 are supported in a bore 46 formed in the body 34 opposite theorifice 32, while the lower portions of the needle stem 35 are supportedcentrally of the valve body 34 within a bore 41 formed in a centralsupporting hub 42. The hub 42 is itself supported inwardly of thevertical, cylindrical side walls of the valve body 34 by the threeradially inwardly extending arms 43, as shown in FIGS. 2 and 3. Morespecifically and as illustrated in FIG. 2, the valve body 34 isgenerally of inverted J-shape having a horizontal, cylindrical inletportion 34a connected to the vertical, generally cylindrical portion ofthe valve body 34b by a 90 elbow portion 340. A flange 55 is formed atthe inlet 34a for connection of the valve to a massecuite supply line(not shown). The upper portions of the needle stem 35 project throughthe valve body and are supported by a guide bushing 44 which is threadedinto a boss 45 integrally formed in the elbow portion 34c, and by thebore 46 formed adjacent the boss. In accordance with the invention, theneedle stem 35 is normally prohibited from rotation by the guide bushingand by the friction of packing ring elements 47 disposed about theneedle stem within the boss cavity 48. Thus, rotation of the lead screw36 will cause the translation of the nut 37 therealong, together withthe stem 35 to vary the size of the discharge outlet 20.

As shown in FIG. 1, two vertical mounting plates 50, 51 are bolted tobosses 54 formed integrally with the valve body 34, which plates 50, 51extend upwardly and parallel to the lead screw 36. A horizontal motorplatform 52 mounting an electric motor 53, or other suitable drive suchas a pneumatic or hydraulic motor, is supported between the plates 50,51, as shown. A gear box 64 is mounted immediately beneath the motor 53,as shown in FIG. 2, which gear box supports and encloses the outer raceof a ball bearing 55. The inner race of bearing 55 is fixed to thereduced diameter lead screw drive shaft 57 to which a worm wheel 58 isalso fixedly mounted. A nut 59 threaded on the outer end of the shaft 57urges the wheel 58 against the inner race of bearing 55 through a spacer60. The worm wheel 58 is driven by a worm 59 supported on a shaft 66journaled in the gear box on an axis perpendicular to the axis of thelead screw 36. The worm wheel is rotated by a sprocket wheel 67 carriedon one end of the support shaft 66, which sprocket is driven by a rollerchain 61 which transmits the drive of a bidirectional motor 53 thereto,in known fashion, through a sprocket 68. As indicated in FIG. I, thechain is covered by a suitable chain guard 62.

As will be understood and in accordance with the principles of theinvention, the rotation of the lead screw 36 causes the needle stem 35to be translated upwardly or downwardly (depending upon the direction ofrotation thereof) through the threaded nut 37. The precise setting ofthe valve orifice may be effected through the controlled operation ofthe motor 53. More specifically, the amount of massecuite to bedelivered at any instant through the valve 10 is remotely controlledthrough a servo control system which selectively energizes the motor 53.For safety purposes, the motor 53 will be automatically stopped ateither of the extreme limit positions of the valve stem assembly (needle31 seated in plate 33 or drive nut 37 adjacent gear box 64) by a limitswitch 70 having switch arms 71 and 72 carefully positioned at points inthe vertical path of the handwheel 38 corresponding to the desired limitpositions. Accordingly, the limit switch 70 includes two sets ofcontacts which-are appropriately wired into the motor control circuitryin a manner to prevent energizing of the motor in a closing directionwhen the valve is completely closed, when the needle 31 is seated, andlikewise to prevent energizing of the motor in an opening direction whenthe valve stem is at its upper limit of travel. Thus. when the handwheel38 contacts either of the limit arms 71, 72, it will cause the motor tobe automatically deenergized, thereby stopping further rotation of thestem 35.

In accordance with an important aspect of the present invention, it ispossible to control the size of the valve opening 20, defined by thecooperation of the needle 31 and orifice 32, manually and independentlyof the electric motor 53. The lead screw 36 is restrained againstrotation, relative to the drive nut 37, by the meshing of the worm wheeland worm. Accordingly, the needle stem may be translated with respect tothe lead screw 36, by manually rotating the handwheel 38 and the nut 37carried thereby. The manual rotation of the nut 37 through the handwheel38 will, of course, selectively displace the needle stem 35 and theneedle 31 carried thereby with respect to the orifice plate 33 inaccordance with the direction of the rotation of the handwheel 38. Thusthe handwheel 38 provides the valve 10 with capabilities of alternativeor standby control as well as a direct manual override of the motorcontrol.

In accordance with another important aspect of the present invention, atreatment fluid such as water or syrup or the like, may be introducedupstream of the orifice into the stream of viscous material flowingthrough the valve body 34. The treatment fluid is introduced through aport 80 formed in the hub 42. More specifically, as shown in FIGS. 2 and3, the port 80 leads to a radial passage 81 extending through one of thearms 43 to an annular manifold 82 which communicates with eight axiallyextending conduits 83 which are arranged in the hub 42 concentricallyabout the needle stem 35, as shown best in FIG. 3. As will beunderstood, water or other treatment fluid introduced through the port80 will flow by gravity along the outer walls of the lower portions ofthe stem and about the needle 31 mixing with the massecuite or otherviscous fluid flow- I ing through the valve body 34. Additionally, thevalve body is provided with a steam port for the introduction of steamor other treatment media into the flowing stream of viscous material,should it be desired or necessary. Enlarged openings 93, sealed byplates 94, are also included in the valve body upstream of the hub 42.

As shown in FIG. 1, the valve 10 is bolted through a horizontal plate 89directly to an external top member 91 or the stationary curb structure92 of the centrifugal separator. Advantageously, the discharge outlet20, the size of which, of course, controls the massecuite stream as itflows freely under the influence of gravity into the centrifugal basket,is located as close to the basket 11 as possible, namely, the horizontalplane of the uppermost edge 11a of the rotating basket 11, as shown inFIG. 1. This location of the outlet orifice in the immediate proximityof the rotating basket 11 minimizes the time lag between changes in theflow of massecuite at the flow control point, i.e., the outlet 20, andavoids changes in the flow conditions at the delivery point of themassecuite within the basket. Moreover, the loca tion of the flowrestricting orifice 20 at the final point in the massecuite supply tothe centrifugal machine eliminates any possible interference with ordistortion of the flow of massecuite by elbows, conducting tubes,

or the like, as is the case, for example, where the control valve (suchas a gate valve) is located upstream of a massecuite discharge spoutdisposed above a centrifugal basket.

While the principles of the present invention and particulars of apreferred way of carrying it into practice have been describedhereinabove and illustrated in the accompanying drawings, it will beevident that numerous variations and substitutions may be made by thoseskilled in the art without departing from the substance or contributionof the invention, which is intended to be defined by the appendedclaims.

What is claimed is:

l. A valve for controlling the delivery of a stream of viscous material,comprising:

an elongated valve body having an inlet at one end and a circular outletorifice at the other end;

a conical needle means supported on an elongated valve stem means, saidneedle means being disposed in said orifice and movable axially relativethereto to close the orifice or to define an annular gap for outflow ofa stream of said viscous material;

threaded drive nut means fixedly associated with said valve stem means;rotatable lead screw means in threaded engagement with said drive nutmeans; drive transmission means for rotating said lead screw means tomove said valve stem means axially of said valve body; and mauallyoperable means for rotating said drive nut means relative to said leadscrew means independently of said transmission means. 2. A valveaccording to claim 1, further characterized in that said manuallyoperable means comprises a handwheel fixed to said drive nut means. 3. Avalve according to claim 1, further characterized in that saidtransmission means includes a worm wheel fixed to said lead screw meansanda worm meshing with said worm wheel.

4. A valve according to claim "1, in which said valve body is agenerally cylindrical hollow body having an opening defined in a portionthereof remote from said orifice;

said valve stem means extending axially through the space of said valvebody and being supported in said opening; and

hub means disposed centrally in the space of said valve body andsupporting said stem means therein.

5. A valve according to claim 4, in which said hub means is fixedrigidly to said valve body by at least one arm extending between saidbody and said hub means.

6. A valve according to claim 5, in which said hub means has a manifoldformed therein;

a passage is formed in at least one said arm for conducting fluid intosaid manifold; and

conduit means extend from said manifold between said hub means and saidvalve stem means for delivering said fluid along said valve stem meansto ward said needle means.

7. A valve according to claim 4, in which said opening has packing meansdisposed therein and means pressing said packing means in frictionalengagement with said valve stem means, whereby the latter normally isrestrained from rotation.

8. A valve according to claim 1, including limit means engageable by amember moved axially with said stem means at predetermined limits of arange of movement of said needle means to inactivate a motor actingthrough said drive transmission means to rotate said lead screw means.

1. A valve for controlling the delivery of a stream of viscous material,comprising: an elongated valve body having an inlet at one end and acircular outlet orifice at the other end; a conical needle meanssupported on an elongated valve stem means, said needle means beingdisposed in said orifice and movable axially relative thereto to closethe orifice or to define an annular gap for outflow of a stream of saidviscous material; threaded drive nut means fixedly associated with saidvalve stem means; rotatable lead screw means in threaded engagement withsaid drive nut means; drive transmission means for rotating said leadscrew means to move said valve stem means axially of said valve body;and maually operable means for rotating said drive nut means relative tosaid lead screw means independently of said transmission means.
 2. Avalve according to claim 1, further characterized in that said manuallyoperable means comprises a handwheel fixed to said drive nut means.
 3. Avalve according to claim 1, further characterized in that saidtransmission means includes a worm wheel fixed to said lead screw meansand a worm meshing with said worm wheel.
 4. A valve according to claim1, in which said valve body is a generally cylindrical hollow bodyhaving an opening defined in a portion thereof remote from said orifice;said valve stem means extending axially through the space of said valvebody and being supported in said opening; and hub means disposedcentrally in the space of said valve body and supporting said stem meanstherein.
 5. A valve according to claim 4, in which said hub means isfixed rigidly to said valve body by at least one arm extending betweensaid body and said hub means.
 6. A valve according to claim 5, in whichsaid hub means has a manifold formed therein; a passage is formed in atleast one said arm for conducting fluid into said manifold; and conduitmeans extend from said manifold between said hub means and said valvestem means for delivering said fluid along said valve stem means towardsaid needle means.
 7. A valve according to claim 4, in which saidopening has packing means disposed therein and means pressing saidpacking means in frictional engagement with said valve stem means,whereby the latter normally is restrained from rotation.
 8. A valveaccording to claim 1, including limit means engageable by a member movedaxially with said stem means at predetermined limits of a range ofmovement of said needle means to inactivate a motor acting through saiddrive transmission means to rotate said lead screw means.